The Northeastern region of India is home to the subspecies of Asian honeybee known as A. cerana himalaya Smith. This study aims to observe the significant variations in morphometrics among worker populations of A. c. himalaya in different elevations of the North-Eastern Hill (NEH) Regions of India. The results revealed greater variability in morphometric parameters at higher altitudes than at lower altitudes. The principal component analysis identified five principal components that explain almost 97% of the total variance of the data, with 43.87% in PC1. On evaluating altitude-driven morphometric changes of 43 parameters through multivariate studies, the majority of morphological characteristics showed strong positive correlations with altitude, rainfall and relative humidity, negative correlations with maximum (AMxT) and minimum (AMnT) temperatures. A clustering analysis was conducted on the A. c. himalaya worker populations of the NEH region of India, which resulted in five morpho clusters based on altitudes. This confirms the presence of variation within the intraspecific populations and highlights the ecological implications of the morphological variations in the A. c. himalaya bee species found in the NEH region of India. While these findings align with certain aspects of Bergmann’s rule, it is important to note that the rule classically applies to endotherms across latitudes, and its extension to ectotherms and altitude remains debated and context-dependent. This investigation represents the first extensive morphometric characterization of the indigenous A. c. himalaya subspecies, offering valuable baseline information for conservation and beekeeping, while also highlighting the need for cautious interpretation and further comparative studies across regions and taxa.
Nidhi et al. (Thu,) studied this question.